The following description relates to the detection and analysis of a hoist, rope or both, and in particular, the optical detection and analysis of the hoist, rope or both on a crane.
A crane, such as a mobile crane, typically includes a lower works, or carrier, and an upper works, or superstructure, mounted on the lower works. The lower works includes, for example, a frame, a suspension mounted to the frame, tires mounted to the suspension, and one or more outriggers each having an arm selectively extendable and retractable in a substantially horizontal direction and a jack coupled to the arm selectively extendable and retractable in a substantially vertical direction. The upper works may be rotatably mounted on the lower works to rotate about a vertical axis. The upper works may include, for example, a boom, an operator cab, a counterweight and a hoist for winding and unwinding a rope. The upper works also includes a rotating bed on which the above-noted components are mounted. The hoist is typically mounted at or near a base of the upper works, such as the rotating bed. The rope may extend outward from the hoist, generally along the boom, and hang freely from the tip of the boom. A hook block is typically disposed at a free end of the rope for engaging a load.
The crane is capable of performing a number of movements. For example, the upper works, including the boom, may swing left or swing right (i.e., rotate on the vertical axis counterclockwise or clockwise), the boom may lift up or down (i.e., increase or decrease an angle relative to the horizontal), and the boom may extend or retract telescopically. In addition, the hoist may operate to unwind the rope such that a length of the rope extending from the boom tip increases, or wind the rope such that a length of the rope extending from the boom tip decreases. Winding of the rope may correspond to lifting the load and unwinding the rope may correspond to lowering the load.
Various crane components, including those described above, may be monitored to determine a status of the crane component. Typically, sensors such as proximity sensors, load cells, RFID sensors and the like may be used to detect a crane component. For example, a proximity sensor may detect whether an outrigger is in a fully extended or retracted condition or whether a counterweight is properly positioned condition. Other sensors, such as position sensors or laser distance sensors, may detect a hook block and a boom tip, such that a distance between the hook block the boom tip may be determined. Accordingly, a two-blocking condition may be determined. Further, load cells may detect a load on an outrigger jack. Subsequently, it may be determined whether the outrigger jack is in a deployed condition. Some crane components may be visually detected as well, for example, by the operator or a spotter.
Crane components may also be monitored to determine a service condition and whether a particular component needs to be replaced, repaired or otherwise maintained. Such monitoring may take place at predetermined time intervals or at a predetermined number of service hours. This monitoring may be carried out, for example, by visual inspection of the components.
A particular crane component that requires monitoring is the hoist and rope system. For example, a rope may begin to fray over time or may be damaged in the course of use. In addition, several rope conditions may occur on the hoist as a result of winding or unwinding which may adversely affect crane operations.
Currently, hoist and rope conditions may be monitored visually by an operator, spotter or service technician. The hoist and rope can be monitored both during use of the crane, in between uses, or at predetermined intervals, for example, at scheduled service inspections. Alternatively, some hoist and rope conditions may be monitored using a camera based monitoring system. For example, CN 00010435356 discloses a camera based system for monitoring a rope wound on a hoist drum, to determine if individual rope wraps are parallel and if the wraps are a correct distance apart.
However, manual or visual inspection of the hoist and/or rope may be time consuming, costly, and may be subjective depending on the viewer. In addition, intermittent or regularly scheduled inspections may fail to timely identify a service condition of a component which may affect crane operations. Further, existing camera-based monitoring systems are limited to detecting only certain components and determining relatively few conditions. For example, such systems may detect the rope only while on the hoist, and thus, are limited in the number and types of conditions which may be determined.
Accordingly, it is desirable to provide an image-based hoist and rope detection and analysis system capable of detecting and determining an increased number of conditions as well as other crane conditions based on the analysis of a captured image in which hoist and/or rope are detected.